Vehicle height adjusting apparatus

ABSTRACT

A vehicle height adjusting apparatus includes a suspension spring supporting a sprung weight of a vehicle, a pivotal unsprung member carrying a road wheel and connected to a lower end of the suspension spring so as to pivot in response to deformation of the suspension spring, and a drive mechanism adapted so as to be free from the sprung weight and capable of moving the unsprung member so as to cause the suspension spring to increase or decrease in length and thereby adjusting a vehicle height at the road wheel.

BACKGROUND OF THE INVENTION

The present invention relates to a vehicle height adjusting apparatus.

Heretofore known is a vehicle height adjusting apparatus that includes ascrew drive mechanism by way of which a piston rod of a damper disposedbetween a vehicle body side and a carrier side is connected to thevehicle body side or the carrier side so that the piston rod is movableupward and downward as disclosed in Japanese Patent No. 3294672. Thescrew drive mechanism of the vehicle height adjusting apparatus includesa ball screw and a nut threadedly engaged with each other by way ofballs. The ball screw is rotatably connected to a vehicle body sidemember of the damper or an carrier side member. The nut is connected tothe piston rod or the cylinder, and either of the ball screw or the nutis connected to a drive unit. When the ball screw or nut is driven bythe drive unit, the relative position of the ball screw and nut ischanged, thereby adjusting the vehicle height.

SUMMARY OF THE INVENTION

However, the screw drive mechanism of the vehicle height adjustingapparatus performs adjustment of the vehicle height while supporting allthe weight of the vehicle body (sprung weight), so that the membersconstituting the screw drive mechanism need to have a sufficientstrength. Further, in order to move the unsprung members upward anddownward of the vehicle, the screw drive mechanism must be rotated whilesupporting all the sprung weight, resulting in the necessity of a largeoutput of the drive unit.

It is accordingly an object of the present invention to provide avehicle height adjusting apparatus that can decrease the necessarystrength of the members constituting the apparatus and the necessaryoutput of the drive unit.

To achieve the above object, there is provided according to an aspect ofthe present invention a vehicle height adjusting apparatus comprising asuspension spring supporting a sprung weight of a vehicle, a pivotalunsprung member carrying a road wheel and connected to a lower end ofthe suspension spring so as to pivot in response to deformation of thesuspension spring, and a drive mechanism adapted so as to be free fromthe sprung weight and capable of moving the unsprung member so as tocause the suspension spring to increase or decrease in length andthereby adjusting a vehicle height at the road wheel.

According to another aspect of the present invention, there is provideda vehicle suspension system comprising a suspension member pivotallyconnected at an end portion thereof to a vehicle body side member androtatably supporting a road wheel, a suspension spring disposed betweenthe vehicle body side member and the suspension member, a line memberconnected at one end thereof to the suspension member, and a drive unitinstalled on the vehicle body side member and connected to the other endof the line member, the drive unit being capable of driving the linemember toward and away from the vehicle body side member and therebyadjusting a vehicle height at the road wheel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a torsion beam type suspension systemhaving a vehicle height adjusting apparatus according to a firstembodiment of the present invention;

FIG. 2 is a schematic view of the vehicle height adjusting apparatus ofFIG. 1 when taken in the vehicle width direction;

FIG. 3 is a diagrammatic view of double wishbone type suspension systemhaving a vehicle height adjusting apparatus according to a secondembodiment of the present invention;

FIG. 4 is a perspective view of another torsion beam type suspensionsystem having a vehicle height adjusting apparatus according to a thirdembodiment of the present invention;

FIG. 5 is an enlarged perspective view of a drive mechanism of thevehicle height adjusting apparatus of FIG. 4;

FIG. 6 is a view similar to FIG. 5 but shows a reel of the drivemechanism in a state of having wound more of a wire; and

FIG. 7 is a diagrammatic view of the vehicle height adjusting apparatusof FIG. 4 when taken in the vehicle width direction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring first to FIGS. 1 and 2, a torsion beam type suspension systemhaving a vehicle height adjusting apparatus according to a firstembodiment of the present invention is shown.

The suspension system has a pair of hub carriers 4 rotatably supportingor carrying left and right road wheels 2, respectively and a pair ofleft and right trailing arms (pivotal unsprung members) 6 elongating inthe front-to-rear direction of a vehicle. Carriers 4 are secured to rearend portions of trailing arms 6, respectively. The rear end portions oftrailing arms 6 are secured to torsion beam 8 elongating in the vehiclewidth direction so as to constitute an integral unit. Front end portionsof trailing arms 6 are connected to vehicle body side member 12 by wayof resilient bushings 10, respectively.

Lateral link 14 is pivotally attached at opposite axial ends thereof toan axial end of torsion beam 8 and vehicle body side member 12 by way ofresilient bushings (not shown) so as to incline upward as it extends inthe vehicle width direction from the torsion beam 8 to vehicle body sidemember 12.

Between the joint at which each trailing arm 6 and torsion beam 8 arejoined and vehicle body side member 12 is disposed coil spring(suspension spring) 16 that supports the weight of a vehicle body(sprung weight). Further, shock absorbers 18 are pivotally connected atlower ends thereof to left and right carriers 4 and at upper endsthereof to vehicle body side member 12.

In this embodiment, a pair of drive mechanisms 20 are disposed on theopposite sides of the vehicle body that are opposed in the vehicle widthdirection, for moving trailing arms 6 upward and downward of thevehicle.

Each drive mechanism 20 includes wire (line member) 22 having a lowerend connected to a rearward side of trailing arm 6, reversible motor(drive source) 24 installed on vehicle body side member 12 at a locationabove the place where wire 22 is connected to trailing arm 6, reel 24 asecured to a rotation shaft of motor 24, and spiral spring (resilientmember) 26 wound around reel 24 a and having an end connected to anupper end of wire 22. Reversible motor 24 and reel 24 a constitute adrive unit for driving wire 22 toward and away from vehicle body sidemember 12.

In this connection, the spring constant of spiral spring 26 is set at avalue smaller than that of coil spring 16.

In case the vehicle height is to be decreased, each reel 24 a is drivenby motor 24 of drive mechanism 20 so as to rotate a predetermined numberof turns in the direction indicated by the arrow in FIG. 1. Thepredetermined number of turns of reel 24 a causes spiral spring 26 to bewound around reel 24 a while being resiliently deformed and therebycauses wire 22 to be pulled. By this, coil spring 16 is compressed andbecomes shorter in length, thus causing the vehicle body to movedownward and therefore the vehicle height to decrease.

In case the vehicle height is to be increased, each reel 24 a is drivenby motor 24 of drive mechanism 20 so as to rotate a predetermined numberof turns in the direction opposite to that indicated by the arrow inFIG. 1. The predetermined number of turns of reel 24 a causes spiralspring 26 wound around reel 24 a to be unwound or paid out. This allowscoil spring 16 to become longer in length, thus causing the vehicle bodyto move upward and therefore the vehicle height to increase.

In this connection, in case the vehicle height is to be adjusted by 100mm under the condition in which the weight of the vehicle body is 1500Kg, the spring constant of coil spring 16 is 19.6 N/mm and the springconstant of spiral spring 26 is 1.96 N/mm, the driving force F1 of motor24 and the amount of deformation H of spiral spring 26 required for suchadjustment are the following values, respectively.F1=(19.6−1.9)×100=1764 N  (1)H=100×(19.6−1.96)/1.96=900 mm  (2)

In contrast to this, in case the same vehicle height adjustment is to bemade by means of the conventional vehicle height adjusting apparatushaving the above-described screw drive mechanism that supports theweight of the vehicle body, the driving means is required to produce thefollowing driving force F2.F2=1500×9.8/4=3675 N  (3)

From the equations (1) and (3), the ratio of the driving force F1 ofmotor 24 to the driving force F2 of the conventional driving means isF1/F2=0.48, so that the driving force F1 of motor 24 in this embodimentcan be smaller as compared with that F2 of the conventional vehicleheight adjusting apparatus.

Accordingly, in this embodiment, the output (driving force F1) of motor24 required by drive mechanism 20 in adjustment of the vehicle height isequal to the reaction force of coil spring 16 caused by the deformationthereof. Accordingly, in case the drive mechanism 20 is to be driven, itis not influenced by the sprung weight of the vehicle such that theoutput of motor 24 can be smaller.

Further, work W1 required for carrying out the vehicle height adjustmentof 100 mm under the same condition as described above is the followingvalue in case coil spring 16 is compressed to become shorter in length.W1=1/2×(19600−1960)×0.1²=88.2 N/m  (4)

In contrast to this, work W2 required for elevating the vehicle body by100 mm at each road wheel by means of the conventional vehicle heightadjusting apparatus is the following value.W2=1500×9.8×0.1/4=367.5 N/m  (5)

From the equations (4) and (5), the ratio of work W1 of the vehicleheight adjusting apparatus of this embodiment to work W2 of theconventional apparatus is W1/W2=0.24, so that work W1 of the vehicleheight adjusting apparatus of this embodiment can be smaller than thatW2 of the conventional apparatus.

Further, since each drive mechanism 20 is disposed between vehicle bodyside member 12 and corresponding trailing arm 6 so as to be in parallelrelation with the direction in which coil spring 16 deforms resiliently,the sprung weight is not loaded on each drive mechanism 20, thusenabling the members constituting drive mechanism 20 to be less in thestrength as compared with those of the conventional screw drivemechanism.

Further, since drive mechanism 20 is disposed so as to be in parallelrelation with the direction in which coil spring 16 deforms resiliently,arrangement of drive mechanism 20 does not cause any influence on theheight of a vehicle floor above the ground and is therefore advantageousfrom the point of view of retaining the stroke of the suspension system.

Further, since drive mechanism 20 is simple in structure, it can becompact in size and can be attained at low cost.

Further, the spring constant of spiral spring 26 is set at a valuesmaller than that of coil spring 16 so that spiral spring 26 does notsupport the vehicle body resiliently. Thus, spiral spring 26 can followelongation and contraction of wire 22 that is caused by the stroke ofthe suspension system without delay and can absorb slackness of wire 22efficiently.

Referring to FIG. 3, the vehicle height adjusting apparatus embodied ina double wishbone type suspension system according to a secondembodiment of the present invention will be described. In thisembodiment, like parts and portions to those of the first embodimentwill be designated by like reference characters and will not bedescribed in detail again.

In this suspension system, each carrier 4 that rotatably carriescorresponding left or right road wheel 2 is supported by upper arm 30and lower arm 32. The vehicle body side end portions of upper arm 30 andlower arm 32 are pivotally connected to vehicle body side member 12 byway of resilient bushings 34, 36, respectively.

Further, each shock absorber 18 is disposed so as to have a lower endpivotally connected to lower arm 32 and an upper end pivotally connectedto vehicle body side member 12. Around each shock absorber 18 isdisposed coil spring (suspension spring) 16. By this, the suspensionsystem is adapted to support the vehicle weight (sprung weight).

In this embodiment, there is provided drive mechanism 38 for drivinglower arms 32 upward and downward of the vehicle.

Drive mechanism 38 includes a pair of wires (line members) 40, 42 eachconnected at an end to each of lower arms 32 disposed at the laterallyopposite sides of the vehicle, a pair of fixed pulleys 44, 46 supportingwires 40, 42 in a way as to allow wires 40, 42 to extend inboard orinward with respect to the vehicle width direction, reversible motor(power source) 48 installed on vehicle body side member 12 so as to bepositioned at the widthwise center thereof, reel 48 a fixedly attachedto a rotation shaft of motor 48 and a pair of spiral springs (resilientmembers) 50, 52 wound in the same direction around reel 48 a. Reversiblemotor 48 and reel 48 a constitute a drive unit for driving wires 40, 42inboard and outboard of a vehicle body.

Also, in this embodiment, the spring constant of spiral springs 50, 52is set at a value smaller than that of coil spring 16 so as not tosupport the vehicle body.

In case the vehicle height is to be increased, motor 48 is driven in thenormal direction so as to cause the pair of spiral springs 50, 52 to bewound around reel 48 a. By this, coil springs 16 are resilientlydeformed so as to become shorter in length and cause the vehicle body tomove downward, thus decreasing the vehicle height.

Further, in case the vehicle height is to be lowered, motor 48 is drivento rotate in the direction opposite to the normal direction so as tounwind or pay out the pair of spiral springs 50, 52 having wound aroundreel 48 a. By this, coil spring 16 is caused to increase in length, thusallowing the vehicle body to move upward and thereby increasing thevehicle height.

Accordingly, also in this embodiment, the output of motor 48 required atthe time of adjustment of the vehicle height by means of drive mechanism38 is only the reaction force that is caused by resilient deformation ofcoil spring 16. Accordingly, the driving of drive mechanism 38 is notinfluenced by the sprung weight, thus making it possible to decrease thenecessary output of motor 48.

Further, although motor 48 is required to produce double the output ascompared with motor 24 of drive mechanism 20 shown in FIGS. 1 and 2,adjustment of the vehicle height can be attained by one motor 48, thusmaking it possible to attain drive mechanism 38 that is more simplified.

Referring to FIGS. 4 to 7, the vehicle height adjusting apparatusembodied in another torsion beam type suspension system according to athird embodiment of the present invention will be described. In thisembodiment, like parts and portions to those of the first embodimentdescribed with reference to FIGS. 1 and 2 will be designated by likereference characters and will not be described in detail again.

The suspension system, as shown in FIG. 4, has a pair of carriers 60rotatably carrying a pair of left and right road wheels 2, respectivelyand a pair of left and right trailing arms 62 elongating in thefront-to-rear direction of a vehicle. Carriers 60 are secured to rearside portions of trailing arms 62 (i.e., portions located forward of therear ends), respectively. Trailing arms (unsprung members) 62 areconnected at portions forward of carriers 60 to torsion beam 64elongating in the vehicle width direction so as to constitute anintegral unit. Front end portions of trailing arms 62 are pivotallyconnected to vehicle body side member 12 (refer to FIG. 7) by way ofresilient bushings 10, respectively.

Between the joint where each training arm 62 and each torsion beam 64are joined and vehicle body side member 12 (refer to FIG. 7) is disposedcoil spring 16 so that the suspension system supports thereon thevehicle weight. Further, shock absorbers 18 are disposed so as to bepivotally connected at lower ends thereof to left and right carriers 60and at upper ends thereof to vehicle body side member 12, respectively.

Each drive mechanism 66 in this embodiment includes wire (line member)68 having a lower end connected to a rear end portion of each trailingarm 62 that is located rearward of carrier 60, reversible motor 70installed on vehicle body side member 12 so as to be positioned abovethe joint between trailing arm 62 and wire 68, reel 72 around which wire68 is wound, and worm gearing 74 for transmitting rotation of motor 70to reel 72. Reversible motor 70, reel 72 and worm gearing 74 constitutea drive unit for driving wire 68 toward and away from vehicle body sidemember 12.

Worm gearing 74 includes worm 74 a coaxially fixed to a rotation shaftof motor 70 and worm wheel 74 b meshed with worm 74 a so as to be drivento rotate.

Reel 72, as shown in FIG. 5, includes rotation shaft 72 b rotatablysupported at one end portion thereof on vehicle body side member 12,worm wheel 74 b fixedly attached to the other end portion of rotationshaft 72 b, hollow reel cylinder 72 a rotatably installed on rotationshaft 72 b and spiral spring (resilient member) 72 c disposed insidereel cylinder 72 a and fixedly attached at a radially inner end thereofto rotation shaft 72 b and at a radially outer end thereof to reelcylinder 72 a. In this connection, spiral spring 72 c has a springconstant that is smaller than that of coil spring 16 so that, differingfrom coil spring 16, it does not support the vehicle body.

In case the vehicle height is to be lowered, worm 74 a of worm gearing74 is driven by motor 70 so as to rotate in the direction indicated bythe arrow shown in FIG. 5. Rotation of worm 74 a causes worm wheel 74 bmeshed with worm 74 a to rotate in the direction indicated by the arrowin FIG. 5, thus causing spiral spring 72 c to be resiliently deformedand wound around rotation shaft 72 b. Then, as shown in FIG. 6, togetherwith resilient deformation of spiral spring 72 c, rotation of rotationshaft 72 b is transmitted to reel cylinder 72 a by way of spiral spring72 c. Reel cylinder 72 a that rotates in the direction indicated by thearrow in FIG. 5 winds up and therefore pulls wire 68. By this, coilspring 16 is resiliently deformed so as to decrease in the length, thuscausing the vehicle body to move downward.

Further, in case the vehicle height is to be increased, worm 74 a ofworm gearing 74 is driven by motor 70 so as to rotate by a predeterminednumber of turns in the direction opposite to that indicated by the arrowin FIG. 6. This rotation of worm 74 a is transmitted by way of wormwheel 74 b and spiral spring 72 c to reel cylinder 72 a, thus causingwire 68 having wound around reel cylinder 72 a to be unwound or paidout. By this, coil spring 16 is resiliently deformed so as to increasein length, thus causing the vehicle body to move upward and thereforethe vehicle height to increase.

FIG. 7 is a conceptual view of drive mechanism 66 that is disposedreward of coil spring 16 when taken in the vehicle width direction. Inthe conceptual view, spiral spring 72 c is shown so as to be disposedoutside of reel cylinder 72 a.

Now, assuming that the distance L1 from the pivotal center of trailingarm 62 (i.e., the center of bushing 10) to the center of road wheel 2 is400 mm, and the distance L2 from the pivotal center of trailing arm 62to the joint where wire 68 of drive mechanism 66 is connected to the endportion of trailing arm 62 is 600 mm, adjustment of vehicle height by±30 mm in case the vehicle weight (sprung weight) is 1500 Kg and thespring constant of coil spring 16 is 19.6 N/mm requires a driving forceF3 of motor 70 that is calculated as follows if the spring constant ofspiral spring 72 c is 1.96 N/mm.F3=(19.6−1.96×600/400)×(30×2)×400/600=666.4 N  (7)

On the other hand, the required driving force F2 of the conventionalvehicle height adjusting apparatus wherein the above-described screwdrive mechanism supports the vehicle weight is 3675 N, i.e., F2=3675 Nas is seen from the equation (3).

From the equations (7) and (3), the ratio of the driving force F3 ofmotor 70 in this embodiment to the driving force F2 of the conventionaldriving mechanism is F3/F2=0.18, thus enabling the driving force F3 ofmotor 70 in this embodiment can be smaller as compared with the drivingforce F2 in the conventional vehicle height adjusting apparatus.

Accordingly, in this embodiment, the output (driving force F3) of motor70 that is required by drive mechanism 66 at the time of adjustment ofthe vehicle height is such a value that corresponds only to a reactioncaused by resilient deformation of coil spring 16, so that the drivingof drive mechanism 66 is not influenced by the sprung weight. Further,since worm gearing 74 is provided between motor 70 and reel 72, adriving force can be transmitted from motor 70 to reel 72 but a reactionof coil spring 16 is not transmitted as a rotational force to motor 70,thus making it possible to maintain a set vehicle height withoutrequiring a particular lock mechanism.

Further, since the spring constant of spiral spring 72 c is set smallerthan that of coil spring and at such a small value that spiral spring 72c does not resiliently support the vehicle body. This enables spiralspring 72 c to resiliently deform following movement of wire 68 that iscaused by a stroke of the suspension system and absorb slackness of wire68 with efficiency.

Further, when the torsion beam type suspension system of this embodimentis used as a rear suspension system, the height of the floor of thevehicle body above the ground can be decreased by utilizing the rearwardspace of the vehicle effectively since drive mechanism 66 is disposedrearward of the wheel center. Further, since spiral spring 72 c isdisposed inside cylinder 72 a of reel 72, drive mechanism 66 can besmall-sized, thus making it possible to attain disposition of trailingarm 62 in an upper space with ease.

The entire contents of Japanese Patent Applications P2003-039165 (filedFeb. 18, 2003) and P2003-413478 (filed Dec. 11, 2003) are incorporatedherein by reference.

Although the invention has been described above by reference to certainembodiments of the invention, the invention is not limited to theembodiments described above. Modifications and variations of theembodiments described above will occur to those skilled in the art, inlight of the above teachings. For example, while the embodiments havebeen described with respect to the case where drive mechanism 20, 38 or66 is installed on vehicle body side member 12 and a free end of linemember 22, 40, 42 or 68 is connected to unsprung member 6, 32, or 62,drive mechanism 20, 38 or 66 may be installed on unsprung member 6, 32or 62 and the free end of line member 22, 40, 42 or 68 may be connectedto vehicle body side member. The scope of the invention is defined withreference to the following claims.

1. A vehicle height adjusting apparatus comprising: a suspension springsupporting a sprung weight of a vehicle; a pivotal unsprung membercarrying a road wheel and connected to a lower end of the suspensionspring so as to pivot in response to deformation of the suspensionspring; and a drive mechanism adapted so as to be free from the sprungweight and capable of moving the unsprung member so as to cause thesuspension spring to increase or decrease in length and therebyadjusting a vehicle height at the road wheel, wherein the drivemechanism includes a line member connected at one end thereof to one ofa vehicle body side member and the unsprung member, a drive unitdisposed at the other of the vehicle body side member and the unsprungmember and capable of driving the line member toward and away from theother of the vehicle body side member and the unsprung member, and aresilient member connected to the other end of the line member, thedrive unit being capable of driving the line member by way of theresilient member, and wherein the drive unit comprises a reel, and theresilient member includes a spiral spring connected to the other end ofthe line member and wound around the reel, the drive unit being capableof varying an amount by which the spiral spring is wound around thereel.
 2. A vehicle height adjusting apparatus according to claim 1,wherein the drive mechanism is disposed between a vehicle body sidemember and the unsprung member so as to be in parallel relation with thedirection in which the suspension spring deforms resiliently.
 3. Avehicle height adjusting apparatus according to claim 1, wherein thedrive mechanism is disposed rearward of the suspension spring.
 4. Avehicle height adjusting apparatus according to claim 1, wherein thespiral spring is smaller in spring constant than the suspension spring.5. A vehicle height adjusting apparatus comprising: a suspension springsupporting a sprung weight of a vehicle; a pivotal unsprung membercarrying a road wheel and connected to a lower end of the suspensionspring so as to pivot in response to deformation of the suspensionspring; and a drive mechanism adapted so as to be free from the sprungweight and capable of moving the unsprung member so as to cause thesuspension spring to increase or decrease in length and therebyadjusting a vehicle height at the road wheel, wherein the drivemechanism includes a line member connected at one end thereof to one ofa vehicle body side member and the unsprung member and a drive unitdisposed at the other of the vehicle body side member and the unsprungmember and capable of driving the line member toward and away from theother of the vehicle body side member and the unsprung member, whereinthe drive unit includes a reel connected to the other end of the linemember and rotatable to wind up the line member, a drive source fordriving the reel and a worm gearing for transmitting power from thedrive source to the reel, the worm gearing including a worm connected tothe drive source and a worm wheel attached to the reel so as to berotatable together with the reel in response to rotation of the worm,and wherein the reel includes a rotation shaft rotatably mounted at oneend portion thereof on the vehicle body side member and connected at theother end portion thereof to the worm wheel so as to rotate togethertherewith, a hollow reel cylinder rotatably mounted on the rotationshaft and a resilient member disposed inside the reel cylinder andhaving opposite ends connected to the rotation shaft and the reelcylinder, respectively.
 6. A vehicle height adjusting apparatusaccording to claim 5, wherein the resilient member comprises a spiralspring having a radially inner end connected to an outer circumferentialsurface of the rotation shaft and a radially outer end connected to aninner circumferential surface of the reel cylinder.
 7. A vehicle heightadjusting apparatus according to claim 6, wherein the spiral spring issmaller in spring constant than the suspension spring.
 8. A vehicleheight adjusting apparatus according to claim 5, wherein the drivemechanism is disposed between a vehicle body side member and theunsprung member so as to be in parallel relation with the direction inwhich the suspension spring deforms resiliently.
 9. A vehicle heightadjusting apparatus according to claim 5, wherein the drive mechanism isdisposed rearward of the suspension spring.
 10. A vehicle suspensionsystem comprising: a suspension member pivotally connected at an endportion thereof to a vehicle body side member and rotatably supporting aroad wheel; a suspension spring disposed between the vehicle body sidemember and the suspension member; a line member connected at one endthereof to the suspension member; and a drive unit installed on thevehicle body side member and connected to the other end of the linemember, the drive unit being capable of driving the line member towardand away from the vehicle body side member and thereby adjusting avehicle height at the road wheel, wherein the drive unit includes a reelconnected to the other end of the line member, a reversible motordrivingly connected to the reel, and a spiral spring wound around thereel, the other end of the line member being connected to the reel byway of the spiral spring.
 11. A vehicle suspension system according toclaim 10, wherein the suspension member is elongated in a front-to-reardirection of a vehicle so that said end portion is a front end portion.12. A vehicle suspension system according to claim 11, wherein thesuspension member rotatably supports the road wheel at a rear endportion thereof, the line member being connected to the rear end portionof the suspension member.
 13. A vehicle suspension system according toclaim 11, wherein the suspension member rotatably supports the roadwheel at a rear side portion located forward of a rear end, the linemember being connected to the rear end of the suspension member.
 14. Avehicle suspension system according to claim 10, wherein the suspensionmember is elongated in a vehicle width direction so that said endportion is an inboard end portion.
 15. A vehicle suspension systemaccording to claim 14, wherein the suspension member rotatably supportsthe road wheel at an outboard end portion thereof, the line member beingconnected to the outboard end portion of the suspension member.
 16. Avehicle suspension system according to claim 10, wherein the spiralspring is smaller in spring constant than the suspension spring.
 17. Avehicle suspension system comprising: a suspension member pivotallyconnected at an end portion thereof to a vehicle body side member androtatably supporting a road wheel; a suspension spring disposed betweenthe vehicle body side member and the suspension member; a line memberconnected at one end thereof to the suspension member; and a drive unitinstalled on the vehicle body side member and connected to the other endof the line member, the drive unit being capable of driving the linemember toward and away from the vehicle body side member and therebyadjusting a vehicle height at the road wheel, wherein the drive unitincludes a reel connected to the other end of the line member and areversible motor drivingly connected to the reel, and wherein the reelincludes a hollow reel cylinder, a rotation shaft rotatably mounted onthe vehicle body side member and rotatably supporting thereon the reelcylinder and a spiral spring disposed inside the reel cylinder so as towind around the rotation shaft and having opposite ends connected to thereel cylinder and the rotation shaft, respectively, the drive unitfurther including a worm gearing transmitting power from the motor tothe rotation shaft.
 18. A vehicle suspension system according to claim17, wherein the worm gearing comprises a worm wheel connected to therotation shaft to rotate together therewith and a worm meshed with theworm wheel and connected to the motor so as to be driven thereby.
 19. Avehicle suspension system according to claim 17, wherein the suspensionmember is elongated in a front-to-rear direction of a vehicle so thatsaid end portion is a front end portion.
 20. A vehicle suspension systemaccording to claim 19, wherein the suspension member rotatably supportsthe road wheel at a rear end portion thereof, the line member beingconnected to the rear end portion of the suspension member.
 21. Avehicle suspension system according to claim 19, wherein the suspensionmember rotatably supports the road wheel at a rear side portion locatedforward of a rear end, the line member being connected to the rear endof the suspension member.
 22. A vehicle suspension system according toclaim 17, wherein the suspension member is elongated in a vehicle widthdirection so that said end portion is an inboard end portion.
 23. Avehicle suspension system according to claim 22, wherein the suspensionmember rotatably supports the road wheel at an outboard end portionthereof, the line member being connected to the outboard end portion ofthe suspension member.
 24. A vehicle height adjusting apparatuscomprising: a suspension spring supporting a sprung weight of a vehicle;a pivotal unsprung member carrying a road wheel and connected to a lowerend of the suspension spring so as to pivot in response to deformationof the suspension spring; and a drive mechanism adapted so as to be freefrom the sprung weight and capable of moving the unsprung member so asto cause the suspension spring to increase or decrease in length andthereby adjusting a vehicle height at the road wheel, wherein the drivemechanism includes a line member connected at one end thereof to one ofa vehicle body side member and the unsprung member and a drive unitdisposed at the other of the vehicle body side member and the unsprungmember and capable of driving the line member toward and away from theother of the vehicle body side member and the unsprung member, andwherein the drive mechanism further includes a resilient memberconnected to the other end of the line member, the drive unit causingthe resilient member to deform resiliently, thereby driving the linemember.